For your eyes only: The latest theatrical craze features a single performer with a single audience member

Many's the time my enjoyment of a trip to the theatre has been undermined by the walrus-like grunts of a snoozing punter somewhere in Row H. And usually it's tedious having to squeeze past bulbous strangers to get to my seat. On the other hand, half the fun of theatre is sharing this show or that with dozens of other people, all looking the same way in the dark. Theatre is communal, right? It's about disappearing in a crowd, while the talented folks get on with it on stage?

Wrong. Theatre can be, and increasingly is, a solo experience – and a new generation of artists is bent on dividing their audience up into units of one. You want your feet washed? Fancy dancing with a stranger? How about being introduced to a friend's friend on a park bench, or to a glamorous would-be partner on a speed-date? Solo "audience members" are now rushing to participate in encounters that, until recently, few would have called theatre. "It's experiential," says David Jubb, co-artistic director of Battersea Arts Centre (BAC), which is hosting a festival of one-on-one work, "and people want to be part of it."

They must be brave souls – in The Pleasure of Being trilogy, for example, live artist Adrian Howells bathes his audience members naked, cradles and feeds them. (Now that's what I call audience participation.) Howells was an early adopter of one-on-one theatre, having grown frustrated with the conventional alternatives. "I was in a lot of shows," he says, "that involved me divulging personal information to 700 people. And nobody cared. I was never really being met. Perhaps that's the deal with audiences who buy their tickets and sit in the dark: there's a distance between them and the stage."

One-on-one is about reducing that distance, and tackling the impersonality of conventional theatre. "Often in theatre," says Jubb, "you sit in the audience, and feel that you could wave and shout and nothing would happen. It would all just carry on, whether you were there or not." To one-on-one's proponents, this is a betrayal of the unique liveness of theatre. Film and telly can do slick, but only theatre can make an audience feel that its presence is essential, that a real connection is being made. "And one-on-one theatre takes that connection to the nth degree," says Jubb.

The BAC festival brings together 30 such productions, and demonstrates what a "broad church" (in Jubb's words) the movement has become. But the art form's USP is intimacy. These are micro-theatre shows that focus on the minutiae of human relationships that traditional plays often ignore. In Folk in a Box, you'll get sung to, in a box. US artist Nicole Blackman's Beloved – part of London's Lift festival next month– features 14 separate "acts of kindness" offered to the participant by the performers. Several shows at BAC dramatise therapeutic or doctor-patient relationships.

Blackman admits that, when she first made one-on-one work in the early 2000s, "I had to explain to people that it's not necessarily a performance any more than it is a personal service, like a masseuse or a hairdresser or, I suppose, a prostitute." Howells too describes his work in utilitarian terms. "You go to my shows to get yourself revitalised, recharged, re-energised." (But he doesn't "want to push the form just for the sake of it. I'm not interested in doing a live sex show.")

To Howells and others, one-on-one's popularity is a response to the intimacy deficit of 21st-century living. "We are in an age of rapid technological advance, and are more and more disconnected from ourselves, and other people. We spend huge amounts of time in front of computers, and having virtual relationships via email and Facebook. But we don't meet people eye to eye, flesh on flesh. And nothing can substitute for the nourishment of one human being meeting another in real time." One of Howells' shows is called Held, and in it, he just holds the participant in a series of different embraces.

But one-on-one isn't just about supplying intimacy, it's about contemplating it. "A good book never gives you love," says Alexander Devriendt of the Belgian company Ontroerend Goed, "but it gives you an insight into it. A work of art isn't a substitute, it's a mirror." After all, how authentically "intimate" can an encounter with a paid performer be? Devriendt should know: his speed-dating show Internal got into hot water last summer in Edinburgh by exposing the artifice of staged intimacy. "We wanted to show how fast you could build a meaningful relationship with a stranger," says the director. But the show's use (abuse?) of private information relinquished by its audience members reduced some participants to tears, and drew criticism of its "unethical" behaviour.

Devriendt doesn't know whether to be delighted by this – as a Duchamp aficionado, he's excited that art can still shock – or appalled. "I was baffled that people believed in the reality of it," he says. What Internal revealed was that, after years of passively receiving theatre, audiences are unpractised in disentangling reality and illusion; and that one-on-one's exponents have a duty of care towards participants. "One-on-one throws up those questions," says Jubb. "Who is in control? Who's the author? Who is responsible to whom?"

The artists I speak to are all sensitive to these questions – which is what distinguishes one-on-one from traditional "audience participation" (ie, being dragooned on to the stage at a panto and serially humiliated). "I cannot bear audience

participation," says Jubb. "But the work in this season has a huge sense of generosity to and engagement with the audience. A lot of it is edgy, but I don't think there are any pieces that will humiliate you." (Its exponents are determined it should not exclude the shy – or attract only wannabe stars.)

Ant Hampton runs the Rotozaza company, whose show Etiquette has toured the world. He too can't stand audience participation. "When you've got actors on stage, they're coated with this veneer of the rehearsed performer. No matter how hard they try, they know what's coming next and you don't." For participation to be truly non-exploitative, you need to remove this imbalance – or remove actors altogether. Hence Etiquette, in which there are no performers, and in which two audience participants act out the "play" according to instructions delivered over headphones.

If that sounds like the opposite of intimate, be reassured. Hampton argues that Etiquette – and his recent show The Bench, which brokers friendships between strangers on a park bench – encourages a more profound communion between two people than conventional theatre allows between 200. It's an important point – given that one-on-one is often criticised for encouraging selfishness over sharing. Theatre (runs this argument) used to be communal, but now it's becoming just another personalised consumer artefact. It's in response to this charge that Jubb and co-director David Micklem host their festival. Here, numerous one-on-one shows run simultaneously, so that hundreds of participants can share the same experiences over one evening – and talk about them afterwards.

A festival is also the only way to render this type of theatre cost-effective. One-on-one is no money-spinner – but it's got novelty value. The solo-audience show It's Your Film (part of the BAC festival) by the theatre company Stan's Cafe has been performed over 4,500 times around the world. "These shows are high-concept and unique," says director James Yarker. "The criteria against which they're measured are of your own making so your success is guaranteed. And promoters can usually grab the idea quickly." One-on-one is also popular with audiences who often give theatre a wide berth. "When I talk to my friends who hate theatre," says Jubb, "this is the event in our programme they want to see."

Anticipating a wild, unmanageable festival at BAC, with solo shows bursting out of the building's every space, Jubb and Micklem believe that the performing arts world can learn from one-on-one's blurring of the lines between art and participation, authorship and consumption. "With one-on-one, artists are actually creating work with audiences, and really rich ideas come from that," says Jubb. "That may raise hackles among those who see art as being created exclusively by trained artists. But we would say, 'Well, some of it is. And some of the best stuff,' we would say, 'definitely isn't'."

BAC's One-on-One festival runs from 6-18 July (020 7223 2223). 'Etiquette' is at the Gate Theatre, London (020 7229 0706) from 19-30 July. 'Beloved' is at Rainham Hall, London, as part of LIFT (020 7093 6340, liftfestival.com) from 14-18 July